With respect to Engineering drawings, there are recommended scales for reduction and enlargement. These are as follows:- Reduction:- 1:2, 1:5, 1:10, 1:20, 1:50, 1:100, 1:500, and 1:1000 Enlargement:- 2:1, 5:1, 10:1, 20:1, and 50:1. Scales Scaling drawings allow us to draw exceptionally large objects such as houses on any size of paper available to us. To enable this to happen we have to scale every size (dimension) by the same factor. i.e. taking the example of the house, every dimension would have to be divided by say 100. By doing this we are scaling DOWN the size of the house. We can also draw exceptionally small objects larger, examples of which are, the minute electronic chips which are now part of our every day life. They are so small we could not draw them as they are we have to SCALEUP the drawing to be able to draw them. Scales are used a great deal in building drawings. They are used in three main areas, Floor plans, Site plans and Location plans. Each of the three types of drawings have preferred scales. These are as follows:- Type of Drawing Floor Plans Site Plans Location Plans Preferred Scales 1:50 or 1:100 1:200 or 1:500 1:1250 or 1:2500 When we carryout a drawing using the actual dimensions, this is called ‘full size’, or the drawing has been drawn to a scale of 1:1. For every 1mm drawn, 1mm is represented. 1:1 Floor Plans When we carryout a drawing and reduce all the sizes by a factor of 2, i.e. all dimensions are divided by 2, this is scaling down the drawing. This makes the drawing half its original size. What the 1 & 2 represent are, for every 1mm drawn on paper the actual size of the real object is 2mm. 1:2 This type of drawing shows the layout of the rooms inside the building and the position of the doors, windows and important fittings like a bath, sink and toilet. We can also increase the size of an object by any factor. In the example shown opposite the sizes have been increased by a factor of 2. This will make the drawing twice its original size. The 2 is stating that for every 1mm actual size of the object, 2mm have been drawn. If we increased the object by 10 the scale would be 10:1. If we reduced the objects dimensions by twenty the scale would be 1:20. 2:1 Drawn by; David Sommerville Earnock High School
Site Plans Block Plans This type of drawing is concerned with one or more buildings which are within the same area and shows these buildings within their own site (or plot) boundary. The buildings are shown as outlines and boundaries are marked slightly darker. The scale and the north point are both indicated on the drawing. The site is numbered (usually as plots). Waste pipe runs, manholes and trees are also indicated. Important dimensions are shown. A Block Plan or Site Location Drawing shows where the site is located within the local area. It shows roads, outlines of buildings and site boundaries (Garden boundaries). The block plan below shows where a bungalow is situated within the surrounding area. It is normally drawn to a scale of 1:1250. North Point indicator and scale.